Help! Is there anyone that knows?

I have a 1987 626 Mazda, it is a 4-cylinder single cam engine.
A few weeks ago it jumped time. We adjusted the timing belt
adjuster and retimed it. At this point it would start but it was
a little weak on power. The person that timed the car said it
was still a couple teeth off and he would be back to adjust it.
Well, someone else who was trying to be a good citizen and help came and worked on the car and now I have no compression and the car won't start. Before the car jumped time it ran really well. What could have happened to it?